Structural cylinder with conformable exterior

ABSTRACT

A method is provided for the production of structural cylinder with a wound material shell, the method comprising: providing a extruded wood core cylinder; wrapping a flexible material about an exterior surface of the cylinder; applying an adhesive between the interior of the material and the exterior profile of the core; allowing the adhesive to cure providing a structural cylinder with a wrapped material exterior.

RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.13/009,304, filed Jan. 19, 2011 which claims the benefit of U.S.Provisional Applications No. 61/296139, filed Jan. 19, 2010, and No.61/305,204, filed Feb. 17, 2010. Each of these applications is hereinincorporated by reference in their entirety for all purposes.

FIELD OF THE INVENTION

The invention relates to extruded wood cores, and more particularly, toan extruded wood core with a reinforcing web disposed about the exteriorof said score.

BACKGROUND OF THE INVENTION

Wood fiber cores have been used in applications utilized for winding orspooling industrial products. Extruded wood fiber cores, such as thosemanufactured by the assignee since the mid 1960's, have been suitablefor applications where low cost is valued, and where durability is notessential. Wood fiber cores have excellent compressive strength in theaxial direction, but only moderate or poor tensile strength in thetransverse direction. Such fiber cores may be extruded or molded. Woodfiber cores are typically limited to single use as they lack beamstrength, and unwinding of materials from the core can produce cracks,fissures or other structural defects rendering them inoperative.

Solid wood cores are manufactured using labor intensive machining oflumber, gluing, clamping and various steps. While more expensive thanextruded core, the solid wood provides improved structural integrity forheavier materials or multiple use applications. Such solid wood coresare of particular value in intracompany uses. Such solid wood cores haveimproved beam strength.

Similarly, the steel cores are highly durable, but require expensivefabrication and welding, are heavy, and are expensive to ship.

What is needed, therefore, are techniques for providing durable,reusable cylinders manufacturable with low labor.

SUMMARY OF THE INVENTION

One embodiment of the present invention provides a method for theproduction of structural cylinder with a wound material shell, themethod including: providing a extruded wood core cylinder; wrapping aflexible material about an exterior surface of the cylinder; applying anadhesive between the interior of the flexible material and the exteriorprofile of the core; allowing the adhesive to cure providing astructural cylinder with a wrapped material exterior.

Another embodiment of the present invention provides such a methodwherein the flexible material is a sheet of flexible material.

A further embodiment of the present invention provides such a methodfurther comprising application of a plurality of layers of the material.

Still another embodiment of the present invention provides such a methodwherein the material is paper.

A still further embodiment of the present invention provides such amethod wherein the flexible material is selected from the group offlexible materials consisting of: fiber glass, composites, and textiles.

Yet another embodiment of the present invention provides such a methodwherein the flexible material is preferentially applied to parts of theextruded wood core cylinder such that the structural cylinder has anon-cylindrical profile exterior.

A yet further embodiment of the present invention provides such a methodwherein the profile exterior comprises a parabolic frustrum.

Even another embodiment of the present invention provides such a methodfurther comprising applying a finish layer.

One embodiment provides a structural unit, the structural unitincluding: a extruded core comprising wood fiber and a thermoset resinhaving a central hole coaxial with a major axis of the core and anexterior and a plurality of layers of settable material forming a shell,disposed about the exterior of the core.

Another embodiment of the present invention provides such a structuralunit further comprising a finish layer.

A further embodiment of the present invention provides such a structuralunit wherein the finish layer comprises a wood veneer.

Still another embodiment of the present invention provides such astructural unit wherein the finish layer comprises a simulated veneer.

A still further embodiment of the present invention provides such astructural unit wherein the finish layer comprises a plaster skim coat.

Yet another embodiment of the present invention provides such astructural unit wherein the finish layer comprises a patterned paper.

A yet further embodiment of the present invention provides such astructural unit wherein the settable material is selected from the groupof settable materials consisting of coated paper, fiberglass,composites, rubber, synthetic rubber, silicon based polymers, vinyl,elastic polymers, inelastic polymers, and coated textiles.

Even another embodiment of the present invention provides such astructural unit further comprising a water and moisture impenetrablebarrier enlacing the structural unit.

Even another embodiment of the present invention provides such astructural unit wherein the water and moisture impenetrable barriercomprises a heat shrunk polymeric layer.

Still yet another embodiment of the present invention provides astructural unit wherein the water and moisture impenetrable barriercomprises a stretch wrap polymeric layer.

A still yet further embodiment of the present invention provides astructural unit wherein the plurality of layers of settable materialcomprises overlapping layers of preformed tubular segments and adhesive.

The features and advantages described herein are not all-inclusive and,in particular, many additional features and advantages will be apparentto one of ordinary skill in the art in view of the drawings,specification, and claims. Moreover, it should be noted that thelanguage used in the specification has been principally selected forreadability and instructional purposes, and not to limit the scope ofthe inventive subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a prospective drawing illustrating a structural cylinderhaving a web shell configured in accordance with one embodiment of thepresent invention.

FIG. 2 is a prospective drawing illustrating a structural cylinderhaving a wound web shell configured in accordance with one embodiment ofthe present invention.

FIG. 3 is a prospective drawing illustrating a structural cylinderhaving a web shell having a non-cylindrical profile configured inaccordance with one embodiment of the present invention.

FIG. 4 is a prospective drawing illustrating a structural cylinderhaving a web shell and finish layer having a non-cylindrical profileconfigured in accordance with one embodiment of the present invention.

FIG. 5 is a prospective drawing illustrating a structural cylinderhaving a waterproof layer configured in accordance with one embodimentof the present invention.

FIG. 6 is a prospective drawing illustrating a structural cylinderhaving a shell and finish layer having a grove configured in accordancewith one embodiment of the present invention.

FIG. 7 is a cross sectional elevation drawing illustrating a structuralcylinder having a shell layer of split pre-formed tubes configured inaccord with one embodiment of the present invention.

DETAILED DESCRIPTION

In one embodiment of the present invention a core 12 is disposed withina shell 14 forming a structural unit 10. The central core is providedhaving an extruded wood fiber core comprising wood fiber and a resinextruded in a cylindrical or other desired elongate form. Such a core isanalogous to that used in U.S. application Ser. No. 12/328,800 of thesame inventor. This application is hereby incorporated by reference forall purposes.

As illustrated in FIG. 1, a shell 14 is provided disposed around thecore 12 such that a structural unit 10 is formed. In one embodiment, theshell may be configured from tightly wound paper, textile or web. Insuch an embodiment, the paper textile or web is bonded to the core by soas to improve tensile strength afforded by the column, bolstering itshoop strength.

In one such embodiment, the shell 14 may be configured from gummed tape,with or without fiber reinforcement, wound about a central core 12.Other flexible materials, such as textiles, class fiber may beconfigured in sheets or tapes and applied to the cores to form a shell.The flexible material may be adhered to the core with adhesivesincluding but not limited to gums, glues, epoxies, or thermo set resins.In embodiments where smoothness is desired, sheets of material of thelength of the core may be wound around the core to build up the desiredthickness of the shell. Sheets may be shaped to allow for variations inthickness over the profile of the shell 14. Other sheet embodiments mayuse known sheet winding apparatus and methods to achieve smoothcylindrical profiles. Alternatively, as illustrated in FIG. 2, a narrowtape may be wound continuously around the core, until the desiredthickness of shell is achieved. In such an instance, the dimension ofthe core and the width of the tape may dictate the angle at which thetape may be wrapped upon the core. On one embodiment having a 2.75 inchtape, and a 5 inch core external diameter, the angle of application maybe 11 degrees.

One skilled in the art will appreciate that a variety of materials maybe used to wrap the core and to form the column. Materials may includepaper, textiles, fiber glass, graphite and other composites includingbut not limited to nanofibers. Materials selected would be applied in aflexible form and would harden in situ once applied to the core. Methodsof hardening include but are not limited to thermosetting, drying,epoxide curing, and are determined by the matrix in which the materialis embedded.

In alternative embodiments of the present invention, materials disposedabout said core may comprise conformable materials applied in sheets,tapes, or in curable liquid form. Such conformable materials compriserubber, synthetic rubber, silicon based polymers, vinyl, elasticpolymers and inelastic polymers. The degree of conformability may beselected based on the intended use of the finished column. Suchmaterials may be used in combination with or replacing paper, textile,composite or fiber wraps.

In one embodiment of the present invention, the extruded core isprovided with a coating of paper or other web of material such that itis preferentially built up in portions of the column so as to create anon-uniform coating thickness. In such a way, an embodiment, such asthat illustrated in FIG. 3, may be provided wherein a profile analogousto a truncated paraboloid may be provided.

In one embodiment illustrated in FIG. 4, a decorative or aestheticallypleasing finish layer 16 is applied to the column. This finish mayincluded natural or simulated wood veneer, simulated stone veneer,vinyl, textiles, printed or textures papers, or plaster skim coating.

As illustrated in FIG. 5, an additional waterproof layer 18 may beapplied to the surface of the shell 14 and the core 12. It may be in theform of a water and moisture impermeable barrier material such asplastic film or sheeting wrapped around the structural unit 10, or maybe a pre-formed enclosure designed to protect all surfaces of the unit10, including the central channel 20 through the core 12. Waterprooflayers 18 may be configured from heat shrink material or otherwisesecured to the exterior if the unit 10. Waterproof layers 18, may inother embodiments comprise coatings of waterproof resins or curableplastic applied in liquid form to the surfaces desired to be protected.

In one embodiment of the present invention, illustrated in FIG. 6, achannel 22 may be disposed, parallel with the major axis of the unit,and in the shell 14. The channel 22 may either partially or completelytransect the shell 14, and is suitable for either the recessing ofcables or wiring or for the starting of a belt winding on the unit 10.

As illustrated in FIG. 7, in one embodiment, a preformed tube may besplit, the split tube 24 shell may be applied with an adhesive to theexterior if the core 12 in two halves 26. A second tube 28 of slightlylarger inside diameter may be applied in a similar fashion to theexterior of the first split tube and glued or otherwise adhered in sucha way that the seams 32 formed by the split halves 30 of the second tube28 are staggered with respect to the seams 34 formed by the two halves26 of the first tube 24.

Glues used in the adhesion of the papers to the core are chemically andstructurally compatible with the resins used in the core. Degradation ofthe core could compromise strength of the system. Gums typical of thoseused in adhesive tapes and papers may be used. Alternatively, resinssimilar to or identical with that used in the wood fiber extrusion maybe used. In one such embodiment both the extrusion and the glue areUrea-Formaldehyde resins. The setting of the Urea-Formaldehyde resin maybe accelerated using catalysts. Examples of catalysts used includevarious metal salts, such as aluminum sulfate.

The foregoing description of the embodiments of the invention has beenpresented for the purposes of illustration and description. Each andevery page of this submission, and all contents thereon, howevercharacterized, identified, or numbered, is considered a substantive partof this application for all purposes, irrespective of form or placementwithin the application. This specification is not intended to beexhaustive or to limit the invention to the precise form disclosed. Manymodifications and variations are possible in light of this disclosure.

We claim:
 1. A structural unit; said structural unit comprising: aextruded core comprising wood fiber and a thermoset resin having acentral hole coaxial with a major axis of said core and an exterior; aplurality of layers of settable material forming a shell, disposed aboutthe exterior of said core.
 2. The structural unit of claim 1 furthercomprising a finish layer.
 3. The structural unit of claim 2 whereinsaid finish layer comprises a wood veneer.
 4. The structural unit ofclaim 3 wherein said finish layer comprises a simulated veneer.
 5. Thestructural unit of claim 4 wherein said finish layer comprises a plasterskim coat.
 6. The structural unit of claim 2 wherein said finish layercomprises a patterned paper.
 7. The structural unit according to claim 1wherein said settable material is selected from the group of settablematerials consisting of coated paper, fiberglass, composites, rubber,synthetic rubber, silicon based polymers, vinyl, elastic polymers,inelastic polymers, and coated textiles.
 8. The structural unitaccording to claim 1 further comprising a water and moistureimpenetrable barrier enlacing said structural unit.
 9. The structuralunit according to claim 8 wherein said water and moisture impenetrablebarrier comprises a heat shrunk polymeric layer.
 10. The structural unitaccording to claim 8 wherein said water and moisture impenetrablebarrier comprises a stretch wrap polymeric layer.
 11. The structuralunit according to claim 1 wherein said plurality of layers of settablematerial comprises overlapping layers of preformed tubular segments andadhesive.